The present invention relates to a fastener system for repairing a bone fracture and, more particularly, a driver, a measuring device, and a self-drilling, self-tapping, self-counter-sinking, cannulated fastener for use with a guide wire to repair a bone fracture.
While forming a countersunk recess is known in the surgical arts, such recesses are conventionally formed using a separate step and tool. The use of self-countersinking bolts, threaded fasteners, or screws is known in the carpentry and metalworking arts, but such designs are not readily acceptable for use in bone repair. For example, U.S. Pat. No. 5,683,217 to Walther et al. teaches a self-counter-sinking screw wherein the head of the threaded screw has an underside including triangular recesses with edges for cutting or burring a conical countersink in a workpiece. The recesses accommodate material removed by the countersinking. Further, such conventional fasteners are inefficiently driven by applying torque near the rotation axis. A fastener having an improved structure at a reasonable cost, that can form a countersunk recess in a bone to be repaired, that is adapted for use with a guide wire, and that can be efficiently driven by applying torque at its periphery, is needed. Further, there is a need for a measuring device for determining the depth of a fractured bone to be repaired so that an appropriately sized fastener can be selected to repair the fracture.
A fastener assembly for repairing a bone fracture including a cannulated fastener, guide wire, measuring sleeve, and driver maximizes simplicity and cost effectiveness. The fastener provides an improved structure at a reasonable cost for self-tapping, self-drilling, and self-countersinking in a bone to be repaired. Further, the guide wire eases insertion of the fastener and, with the measuring device, simplifies measurement of a bore in bone material, whereby the depth of a fractured bone to be repaired can be easily determined so that an appropriately sized fastener can be selected to repair the fracture. The driver efficiently drives the fastener by applying torque at the periphery of the fastener head.
More particularly, a fastener assembly according to the invention includes a wire having a wire leading end for forming a bore through the bone material and a wire trailing end for extending beyond a near-side cortex of the bone material. The fastener includes a head portion having spaced-apart grooves defining cutting edges, a lower portion having threads, and an axial aperture therethrough for receiving the wire. The fastener is adapted to slide axially over the wire trailing end and be driven toward the wire leading end to countersink in the bone material. A driver including a driver body having an axially disposed aperture therethrough for accommodating the guide wire, and a driver head having fingers adapted to engage the spaced-apart grooves of the fastener head portion, is adapted to drive the fastener in the bone material. A measuring sleeve including a tubular body adapted to be positioned generally coaxially relative the wire trailing end and abutting the bone material includes a graduated scale thereon for comparison to the wire trailing end, whereby the depth of the bore can be determined.